Arctic genetics comes in from the cold
Despite a well-characterized archaeological record, the genetics of the people who inhabit the Arctic have been unexplored. Raghavan
et al.
sequenced ancient and modern genomes of individuals from the North American Arctic (see the Perspective by Park). Analyses of these genomes indicate that the Arctic was colonized 6000 years ago by a migration separate from the one that gave rise to other Native American populations. Furthermore, the original paleo-inhabitants of the Arctic appear to have been completely replaced approximately 700 years ago.
Science
, this issue
10.1126/science.1255832
; see also p.
1004
Because of past limitations in samples and genotyping technologies, important questions about the history of the present-day Greenlandic population remain unanswered. In an effort to answer these questions and in general investigate the genetic history of the Greenlandic population, we analyzed ∼200,000 SNPs from more than 10% of the adult Greenlandic population (n = 4,674). We found that recent gene flow from Europe has had a substantial impact on the population: more than 80% of the Greenlanders have some European ancestry (on average ∼25% of their genome). However, we also found that the amount of recent European gene flow varies across Greenland and is far smaller in the more historically isolated areas in the north and east and in the small villages in the south. Furthermore, we found that there is substantial population structure in the Inuit genetic component of the Greenlanders and that individuals from the east, west, and north can be distinguished from each other. Moreover, the genetic differences in the Inuit ancestry are consistent with a single colonization wave of the island from north to west to south to east. Although it has been speculated that there has been historical admixture between the Norse Vikings who lived in Greenland for a limited period ∼600-1,000 years ago and the Inuit, we found no evidence supporting this hypothesis. Similarly, we found no evidence supporting a previously hypothesized admixture event between the Inuit in East Greenland and the Dorset people, who lived in Greenland before the Inuit.
A multi-disciplinary study of settlement in north-east Greenland found that life in this High Arctic zone was actually favoured by the climate brought in by the Little Ice Age (fifteenth–nineteenth century). Extensive ice cover meant high mobility, and the rare polynyas — small patches of permanently open coastal water — provided destinations, like oases, where huge numbers of migrating marine mammals and birds congregated. One such place was Walrus Island on Sirius Water, a veritable processing plant for walrus, where every spring Thule people stocked up meat supplies that would get the rest of the region through the winter. It was a further drop in the temperature in the mid nineteenth century that led to the region being abandoned.
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